This invention makes injection blow molded articles which can be used as containers or applicators; but which require that both ends of the article must be open. The article may have threaded ends for receiving caps or other means for closing the open ends but in the use of the article it is necessary to have a construction where either of both ends can be opened when necessary.
The articles made by this invention are preferably constructed with end portions having cylindrical cross sections for the portion of the length of the article inward from each end. Such articles cannot be made by ordinary injection molded techniques because only one end of the article is open and additional operations subsequent to blowing are necessary in order to have the other end open. This invention, however, completes the article with both ends open and does not require any subsequent operation.
The prior art has made articles of the type with which this invention is concerned, by injection molding and without blowing. Injection processes without blowing require that the thickness of the article molded be greater than is necessary with injection blow molding. A saving of approximately 40% in the material used can be effected by making articles by this invention which were formerly made by injection molding without blowing.
Special apparatus is necessary for the method of this invention; and both the novel method and apparatus will be described as the specification proceeds.